Hemoglobin derivatives are an important clinical parameter for diagnosis of the oxygen carrying capability of blood hemoglobin. The functional hemoglobin derivatives are known as oxygenated hemoglobin (O2Hb) and deoxy- or reduced hemoglobin (rHb). In many cases, the presence of other, non-functional hemoglobin derivatives, such as carboxyhemoglobin (COHb), methemoglobin (metHb) and/or sulphhemoglobin (sHb) may affect the measurement and/or calculation of oxygen-related parameters, such as oxygen saturation. Indeed, information regarding the presence of other hemoglobin derivatives is important, as these derivatives are non-functional, i.e., they do not have any significant capability to carry oxygen.
Traditionally, hemoglobin derivative measurements are performed using hemoglobin analyzers known as co-oximeters. Current models of tabletop co-oximeters use various numbers of wavelengths to measure and distinguish various hemoglobin derivatives. Some examples of these are the Radiometer ABL700 Series (manufactured by Radiometer Medical A/S, DK-2700 Bronshoj) using128 wavelengths, the AVL912 CO-OXYLITE (manufactured by AVL Scientific Corporation), which is one of the few co-oximeters that measures sHb, uses 17 wavelengths. The AVL912 utilizes a modified spectrophotometer in bandwidths of 6 to 10 nm. The ABL700 uses a typical high-resolution spectrophotometer with a 1½nm bandwidth. The type of technology utilized in the ABL700, and other co-oximeters as well, entails large and highly controlled optical components which results in the tabletop instrument weighing about 75 pounds. In addition, both the AVL912 and ABL700 ultrasonically lyse the red blood cells (RBC) to measure released hemoglobin in plasma. This ultrasonic portion of the system adds size and power requirements to the overall device.
Despite the presence in the art of these large co-oximeters, there is a need, for a point-of-care co-oximeter that is smaller and portable. Such a co-oximeter would enable the direct measurement of functional and/or non-functional hemoglobin derivatives by paramedics, doctors and other health care providers, in the field, in the emergency room or in the medical office.